How Large Igneous Provinces affect global climate, sometimes cause mass extinctions, and represent natural markers in the geological record
How Large Igneous Provinces affect global climate, sometimes cause mass extinctions, and represent natural markers in the geological record
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DOI：
10.1016/j.palaeo.2017.03.014
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发表时间：
2017-07-15
影响因子：
3
通讯作者：
Youbi, Nasrrddine
中科院分区：
文献类型：
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作者：
Ernst, Richard E.;Youbi, Nasrrddine
通过记录古海水/大气变化的沉积物痕量和同位素组成监测，大火成岩省（LIPs）可以对全球气候产生重大影响。对几个lip的改进U-Pb测年（分辨率高于0.1 Myr）证实了长期以来提出的大灭绝与lip之间的联系。最显著的气候效应是由二氧化碳排放的温室气体导致的全球变暖。随后的降温（甚至全球冰期）可能是由与lip相关的玄武岩风化导致的二氧化碳减少和/或硫酸盐气溶胶造成的。与lip相关的其他杀伤机制包括海洋缺氧、海洋酸化、海平面变化、有毒金属输入、必需营养素减少，从而产生灾难性环境影响的复杂网络。值得注意的是，LIP的大小并不是造成环境影响的唯一重要因素。特别重要的是渗出的速率，以及lip产生的火山碎屑物质和到达平流层的挥发性通量的丰度。虽然洪水玄武岩脱气（CO2, SO2，卤素）是重要的（也来自相关的硅火山作用），但大量的这些气体是从富含挥发物的沉积岩（如蒸发岩和煤层）中释放出来的，这些气体被LIPs的侵入成分加热。反馈很重要，例如全球变暖导致包合物不稳定，从而释放更多温室气体，加剧全球变暖。从广义上讲，lip可以影响（甚至诱导）冰库、温室和温室气候状态之间的变化。然而，具体的影响、严重程度和时间顺序对每个LIP都是特定的。基于显生宙记录中显示的一系列由LIP引起的环境影响，我们认为LIP事件代表了前寒武纪的有用时间标记，可以代表沉积记录中保存的一些重要的全球环境变化。(C) 2017 Elsevier B.V.版权所有
Large Igneous Provinces (LIPs) can have a significant global climatic effect as monitored by sedimentary trace and isotopic compositions that record paleo-seawater/atmosphere variations. Improved U-Pb dating (with better than 0.1 Myr resolution) for several LIPs is confirming a long-proposed mass extinction-LIP link. The most dramatic climatic effect is global warming due to greenhouse-gases from LIPs. Subsequent cooling (and even global glaciations) can be caused by CO2 drawdown through weathering of LIP-related basalts, and/or by sulphate aerosols. Additional kill mechanisms that can be associated with LIPs include oceanic anoxia, ocean acidification, sea level changes, toxic metal input, essential nutrient decrease, producing a complex web of catastrophic environmental effects. Notably, the size of a LIP is not the only important factor in contributuing to environmental impact. Of particular significance are the rate of effusion, and the abundance of LIP-produced pyroclastic material and volatile fluxes that reach the stratosphere. While flood basalt degassing (CO2, SO2, halogens) is important (and is also from associated silicic volcanism), a significant amount of these gases are released from volatile-rich sedimentary rocks (e.g. evaporites and coal horizons) heated by the intrusive component of LIPs. Feedbacks are important, such as global warming leading to destabilization of clathrates, consequent release of further greenhouse gases, and greater global warming. In the broadest sense LIPs can affect (or even induce) shifts between Icehouse, Greenhouse and Hothouse climatic states. However, the specific effects, their severity, and their time sequencing is specific to each LIP. Based on the robust array of environmental effects due to LIPs, as demonstrated in the Phanerozoic record, it is suggested that LIP events represent useful time markers in the Precambrian Era as proxies for some significant global environmental changes that are preserved in the sedimentary record. (C) 2017 Elsevier B.V. All rights reserved.